The effect of limited mobility of adspecies on the rates of desorption and reaction

Abstract

In a multicomponent system, if the mobility of the adspecies characteristic of the crystal temperature is low, the details of the dosing procedure such as dosing sequence and temperature can have a significant effect on the resulting configuration of the adspecies. This, in turn, can lead to a dependence of the TPD/TPR spectra on the details of the dosing procedure. This is illustrated through a simple kinetic lattice-gas model that takes into account the limited mobility of one or more adspecies. On the basis of this kinetic lattice-gas model, expressions are derived for the effect of surface diffusion of the adspecies on the rate of a bimolecular reaction taking place on the crystal surface. An attractive feature of the proposed scheme is the ease with which lateral interactions between the adspecies can be included in the analysis.